Radio Cab Murder

Fred Martin finds work as a Taxicab driver after serving a term in prison for safe-cracking. He is approached by a gang that recruits ex-cons, but, wishing to go straight, he informs the police and they send him undercover to join the gang and expose its leader. But the gang discovers Martin's identity and tries to kill him by locking him in a deep freezer. Martin is saved by his cabby friends who ride to the rescue and corner crooks.